In humans, there is a fine balance between energy intake and energy expenditure.
Energy intake is in the form of food and energy expenditure is in the form of the basal metabolic rate and physical activity.
The difference between energy intake and energy expenditure is the net energy balance. If intake exceeds expenditure, then a net positive energy balance occurs.
Energy expenditure depends on a number of factors.
This includes the starting body weight the basal metabolic rate, and physical activity.
With regards to physical activity, there are several key variables including the frequency, intensity, duration, and type of activity done.
Let us now examine energy consumption. One honey glazed donut is shown which has approximately 300 kilocalories.
The energy intake from the consumed donut is equal to the energy consumed by moderate walking for 30-60 minutes, at 3.0 miles per hour.
If an individual walks for an hour at 3 miles per hour.
They will expend approximately 300 kilocalories, the same as what was contained in the consumed donut.
If an individual walks daily for one hour at approximately 3 miles per hour. This type of activity would lead to weight loss. This assumes that the individual does not consume any extra calories and has a net negative energy expenditure.
If this activity continues for a period of two to four months, body weight is reduced as depicted.
The initial weight loss is the result of a negative net energy balance.
The negative energy balance is because energy expenditure exceeds energy intake.
After the initial weight loss, the individual continues to do the same type of exercise, that is, 1 hour of moderate walking daily.
The chart depicts changes in body weight over time.
Individuals are surprised and frustrated that his weight is not continuing to decrease despite regular walking.